Apparatus and method for evaluating a formation

ABSTRACT

An apparatus and method for evaluating a formation is presented. The apparatus comprises a tubular string deployed into a wellbore penetrating the formation, where the tubular string has a longitudinal flow passage therethrough. A flow sub in the tubular string provides fluid communication between the longitudinal flow passage in the tubular string and an annulus between the tubular string and a wall of the wellbore. A wireline tool is attached proximate a bottom end of the flow sub. A telemetry module proximate the flow sub provides communication between the wireline tool and a surface system, without the use of a wireline to the surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to logging of subsurface reservoirs andmore particularly to pipe conveyed logging.

2. Description of the Related Art

Ordinarily, gravity is used to pull logging tools along and into a wellborehole for conducting logging operations. When a well is highlydeviated from vertical, the force exerted by gravity may not besufficient to draw the logging tool through a deviated portion of thewell. Many oil wells are deviated. For example, an offshore platformcommonly has many wells drilled from the platform into various portionsof a targeted formation that surrounds the location of the platform.While some of the wells might be approximately vertical, most of thewells extending from the platform will deviate at various angles intothe formations of interest and some may involve deviations up to, orabove, horizontal. Gravity conveyed logging tools supported on wirelineslose the effect of gravity for forcing the tool through the hole andsimply do not have sufficient motive force to traverse the deviated holeto the zone to be logged. In many instances, the logging tool must bepushed through the deviated well to the zone of interest to ensure thatthe logging tool is located at the requisite location in the deviatedhole. It is desirable therefore that the logging tool be fixed to theend of a string of sufficiently stiff pipe to log along the deviatedwell at the zone of interest. In many cases, this requires using largepipe, such as drill pipe, to have the stiffness required for loggingthese sections.

A known method for logging highly deviated wells, disclosed in U.S. Pat.No. 4,457,370, to Wittrisch, consists of the following steps. A welllogging tool is secured to the bottom of a section of drill pipe, insidea protective sleeve, and the tool is lowered into the well as additionalsections of pipe are assembled. An electrical connector attached to theend of a wireline cable is then inserted into the drill pipe, the cableis passed through a side entry sub mounted on top of the drill stringand the connector is pumped down through the drill pipe into engagementwith a mating connector attached to the logging tool to effectconnection of the tool to the cable and therefore the surface controlequipment. Then other sections of drill pipe are added, the portion ofthe cable above the side entry sub running outside the drill pipe, untilthe tool reaches the bottom of the section to be logged. Then thelogging operation is performed as the drill pipe is moved through thedesired section.

The running of the cable and the additional care and complexity requiredto protect the cable during pipe movement increase the time required toobtain a log. In addition the making of a wet connect is commonly proneto failure requiring additional time and effort to correct.

There is a demonstrated need for providing an apparatus and method forlogging a highly deviated wellbore that does not require the running ofa wireline cable or the making of a wet connect.

SUMMARY OF THE INVENTION

In one aspect of the present invention, an apparatus for evaluating aformation comprises a tubular string deployed into a wellborepenetrating the formation, where the tubular string has a longitudinalflow passage therethrough. A flow sub in the tubular string providesfluid communication between the longitudinal flow passage in the tubularstring and an annulus between the tubular string and a wall of thewellbore. A wireline tool is attached proximate a bottom end of the flowsub. A telemetry module proximate the flow sub provides communicationbetween the wireline tool and a surface system, without the use of awireline to the surface.

In another aspect, a method for evaluating a formation comprisesdeploying a tubular string into a wellbore penetrating the formation.Fluid communication is provided between a longitudinal flow passage inthe tubular string and an annulus between the tubular string and a wallof the wellbore using a flow sub attached to the tubular string. Aparameter of interest is measured with a wireline tool attached to thetubular string below the flow sub. Communication between the wirelinetool and a surface system is accomplished without the use of a wireline.

BRIEF DESCRIPTION OF THE DRAWINGS

For detailed understanding of the present invention, references shouldbe made to the following detailed description of the embodiments, takenin conjunction with the accompanying drawings, in which like elementshave been given like numerals, wherein:

FIG. 1 is a drawing of a logging system according to at least oneembodiment of the present invention;

FIG. 2 is a blown up portion of bottom assembly 30 of FIG. 1;

FIG. 3 is a drawing showing an example of multiple sample tanks in aformation test tool; and

FIG. 4 is a block diagram of the interrelationship of several componentsof the present invention.

DESCRIPTION OF EMBODIMENTS

FIGS. 1 and 2 show an exemplary embodiment of the present invention. Rig5 supports a string 13 of jointed pipe in borehole 15, also called awellbore, that extends through formation 20. As shown, borehole 15 ishighly deviated and may include substantially horizontal sections. Asused herein, highly deviated refers to wellbores that are deviated fromvertical by about 70 degrees, or more. String 13 is made up of pipesections 10 joined together at threaded connections 12. The pipe may bedrill pipe of the type known in the art. String 13 extends in borehole13 into a subterranean formation 20. Bottom assembly 30 is attached tothe bottom of string 15 and comprises telemetry module 35, and flow sub31. Attached below flow sub 31 are wireline logging tools 32A and 32B.As one skilled in the art will appreciate, and as used herein, awireline tool is intended to be a tool designed to be commonly deployedinto and out of the wellbore on an electrical wireline cable, and isdistinguished from tools designed for use during measurement whiledrilling (MWD) operations. Commonly, wireline tools are not designed tosurvive the shock, vibration, and torsion of the drilling operation, asrequired by MWD tools. It is understood, in the context of the presentinvention, that minor mechanical modifications to a wireline tool tomechanically interface the tool for the present invention, do not alterthe nature of the tool as a wireline tool.

As shown, tool 32A is a formation test tool. Logging tool 32B comprisesa logging tool that may include, but is not limited to, at least one of:a nuclear magnetic resonance logging tool (NMR); a resistivity tool; anda nuclear density tool. Such tools are used to determine variousparameters of interest of the formation including, but not limited to:formation resistivity, formation porosity, and formation permeability.Multiple wireline logging tools may be connected together in a loggingstring below flow sub 31. It should be noted that there is nosignificance to the specific location of particular logging tools in thelogging string. For example, if multiple wireline tools are connectedbelow flow sub 31, formation test tool 32A may be located at anylocation in the logging string.

Surface pump 3 pumps fluid 38 through string 13 and down through bottomassembly 30. Fluid 38 exits through flow port 50 in flow sub 31 into theannulus between the string 13 and the wall 14 of borehole 15 where itreturns to the surface. While only one flow port 50 is shown, additionalports are located around the circumference of flow sub 31. Energyconductor 51 is disposed within the body of flow sub 31 and enablespower and information to be communicated between wireline logging tools32A and 32B and pulser 53, described below. Alternatively, multipleconductors may be routed in similar fashion.

Fluid 38 provides flow energy to power turbine/alternator 52 (shown incutaway inside telemetry module 35, and in FIG. 2) to generatesufficient electrical power to operate the downhole logging tools andother downhole devices described herein. Such turbine/alternators areknown in the art and are not discussed, in detail, here.

Telemetry module 35 also contains oscillating shear valve pulser 53, seeFIG. 2, wherein rotor 60 oscillates proximate stator 61 to restrict aportion of flow of fluid 38 thereby generating pressure signals 41 thatpropagate to the surface through fluid 38. Pressure signals 38 aredetected by transducer 7 that is in fluid communication with the outputflow line of pump 3. Transducer 7 is commonly a pressure transducer of akind known in the art. Alternatively, transducer 7 may be a flowtransducer in line with the pump output detecting changes in flowrelated to pressure signals 41. For additional details of the operationof oscillating shear valve pulser 53, see U.S. Pat. No. 6,626,252,assigned to the assignee of this application and which is incorporatedherein by reference. While described herein as used with a shear valvepulser, any suitable downhole mud pulser is intended to be within thescope of the present invention. Such pulsers include, but are notlimited to: positive pulsers, negative pulsers, and continuous, alsocalled siren, pulsers. In addition, surface located downlink pulser 4transmits pulses 42 from the surface controller 8 to the downholesystem. Pulses 42 contain instructions and status information used foroperating the downhole system.

Alternatively, other types of transmission schemes known in the art,that do not employ a wireline connection between the surface and thewireline tool, are intended to be within the scope of the presentinvention. These include, but are not limited to: acoustic transmissionthrough the pipe wall and electromagnetic telemetry.

In one embodiment, wireline tool 32A is a formation test tool such asthose described in U.S. Pat. Nos. 5,303,775; 5,377,755; 5,549,159;5,587,525; 6,420,869; 6,683,681; 6,798,518; and published application US2004/0035199 A1, each of which is assigned to the assignee of thisapplication, and each of which is incorporated herein by reference.Anchors 36 and sample probe 34 are extendable from the body of tool 32Ato force sample probe 34 into contact with wellbore wall 14 and henceinto fluid communication with formation 20. In one embodiment, asillustrated in FIG. 3, the tool 32A of FIG. 1 is shown to incorporate abi-directional piston pump mechanism shown generally at 124 which isillustrated schematically. Within the tool 32A is also provided at leastone and preferably a plurality of sample tanks such as exemplary tanks126 and 128, which may be of identical construction if desired. Thepiston pump mechanism 124 defines a pair of opposed pumping chambers 162and 164 which are disposed in fluid communication with the respectivesample tanks via supply conduits 134 and 136. Discharge from therespective pump chambers to the supply conduit of a selected sample tank126 or 128 is controlled by electrically energized three-way valves 127and 129 or by any other suitable control valve arrangement enablingselective filling of the sample tanks. The respective pumping chambersare also shown to have the capability of fluid communication with thesubsurface formation of interest via pump chamber supply passages 138and 140 which are defined by the sample probe 34 of FIG. 1 and which arecontrolled by appropriate valving. The supply passages 138 and 140 maybe provided with check valves 139 and 141 to permit overpressure of thefluid being pumped from the chambers 162 and 164 if desired. Whiledescribed with two sample tanks, additional sample tanks may be added asdesired. Additional details of the operation and design of tool 32A arecontained in the incorporated references. Parameters of interest of thesampled fluid and the formation may be determined with sensors such as,for example, optical sensors, density sensors, pressure sensors, andtemperature sensors incorporated in tool 32A. The parameters include,but are not limited to, formation pressure, sample fluid refractiveindex, sample fluid bubble-point, sample fluid density, sample fluidresistivity, and sample fluid composition.

In one embodiment, see block diagram in FIG. 4, wireline tools 32A-D aresubstantially unmodified for use in the present invention. As such, thepower, commands, and data transmission to and from wireline tools 32A-Dare substantially the same as if the tools were connected by aconventional wireline to the surface. This capability allows use of avariety of off-the-shelf logging tools in the present invention.Downhole controller 405 contains suitable circuitry in interface module406 to emulate the appropriate functions necessary to operate andcontrol wireline tools 32A-D. Controller 405 also comprises a processor407 and memory 408. At least a portion of memory 408 contains programmedinstructions for use by interface module 406 in the control of theoperation of wireline tools 32A-D. Additional circuitry (not separatelyshown) is adapted to receive power form turbine-alternator 52 andappropriately distribute the power to the downhole components.Additional circuitry and instructions stored in downhole controller 405are used to process the measurement data received form wireline tools32A-D and to format this information for transmission by the mud pulsesystem to the surface. In addition, because the volume of data collectedby the wireline tools 32A-D is commonly orders of magnitude greater thanthe capacity of the telemetry channel 401, when using mud pulse, themeasurement data or suitable subsets thereof may be stored in memory 408for later retrieval when the tools are returned to the surface.Programmed instructions resident in controller 405 are used to determinethe appropriate transmission and storage protocols.

In one embodiment, surface system 400 contains surface controller 8 thatsends commands via downlink pulser 4 to command initiation of variousdownhole functions, such as, for example performing a formation test.The commands, encoded as pulses 42 are received by a suitable sensor intelemetry module 35, such as for example, a pressure sensor (notseparately shown). Once the commands are received and interpreted,downhole controller 405 assumes substantially autonomous control of theformation test. This may include data acquisition and interpretation todetermine that a suitable result is obtained. Instructions and decisionrules programmed into controller 405 are used to control this operation.Other downlink commands may, for example, cause changes in the encodingand pulsing format to enhance detection at the surface.

While described herein as a system used in a highly deviated wellbore,it is intended that the invention described herein is also to be usedfor deploying heavy wireline tools, or heavy strings of tools, that maybe too heavy to be safely conveyed into and out of wellbores that arenot highly deviated, including vertical wellbores.

The foregoing description is directed to particular embodiments of thepresent invention for the purpose of illustration and explanation. Itwill be apparent, however, to one skilled in the art that manymodifications and changes to the embodiment set forth above arepossible. It is intended that the following claims be interpreted toembrace all such modifications and changes.

1. An apparatus for evaluating a formation, comprising: a tubular stringdeployed into a wellbore penetrating the formation, the tubular stringhaving a longitudinal flow passage therethrough; a flow sub in thetubular string, said flow sub providing fluid communication between thelongitudinal flow passage in the tubular string and an annulus betweenthe tubular string and a wall of the wellbore; a wireline tool attachedproximate a bottom end of the flow sub; and a telemetry module proximatethe flow sub providing communication between the wireline tool and asurface system, without the use of a wireline to the surface.
 2. Theapparatus of claim 1, further comprising a downhole power source.
 3. Theapparatus of claim 2, wherein the downhole power source comprises aturbine-alternator disposed in a fluid flowing in the axial flow passageand generating electrical power therefrom.
 4. The apparatus of claim 1,wherein the tubular string comprises drill pipe.
 5. The apparatus ofclaim 1, wherein the wireline tool comprises at least one of: aformation test tool; a resistivity tool, a nuclear tool, and a nuclearmagnetic resonance tool.
 6. The apparatus of claim 1, wherein thetelemetry module comprises a mud pulser transmitting encoded pulses inthe flowing fluid that are detected by the surface system.
 7. Theapparatus of claim 1, wherein the surface system comprises a surfacepulser transmitting a downlink signal to the telemetry module.
 8. Theapparatus of claim 7, wherein the downlink signal comprises commands foroperation of at least one of the wireline tool and the telemetry module.9. The apparatus of claim 1, wherein the telemetry module comprises acontroller having a processor and a memory.
 10. The apparatus of claim9, wherein a signal from the wireline tool is stored in the memory inthe telemetry module.
 11. The apparatus of claim 1, wherein the wellborecomprises a highly deviated wellbore.
 12. A method for evaluating aformation, comprising: deploying a tubular string into a wellborepenetrating the formation; providing fluid communication between alongitudinal flow passage in the tubular string and an annulus betweenthe tubular string and a wall of the wellbore using a flow sub attachedto the tubular string; measuring a parameter of interest with a wirelinetool attached to the tubular string below the flow sub; andcommunicating between the wireline tool and a surface system without theuse of a wireline.
 13. The method of claim 12, further comprisingsupplying electrical power proximate the flow sub.
 14. The method ofclaim 12, wherein the tubular string comprises drill pipe.
 15. Themethod of claim 12, wherein the wireline tool is chosen from the groupconsisting of: a formation test tool; a resistivity tool, a nucleartool, and a nuclear magnetic resonance tool.
 16. The method of claim 12,wherein the step of communicating between the wireline tool and asurface system without the use of a wireline comprises generatingencoded mud pulses in a fluid and detecting the encoded pulses at thesurface.
 17. The method of claim 12, wherein the step of communicatingbetween the wireline tool and a surface system without the use of awireline comprises transmitting a downlink signal from the surfacesystem to a telemetry module proximate the wireline tool.
 18. The methodof claim 17, wherein the downlink signal comprises commands foroperation of at least one of the wireline tool and the telemetry module.19. The method of claim 17, wherein the telemetry module comprises acontroller having a processor and a memory.
 20. The method of claim 12,wherein a signal from the wireline tool is stored in the memory in thetelemetry module.
 21. The method of claim 13, wherein the step ofsupplying electrical power proximate the flow sub comprises inserting aturbine-alternator disposed in a flowing fluid downhole and generatingelectrical power therefrom.